The invention relates to a process for computer-controlled manufacture of dentures for restoration of at least one tooth or an area of the jaw or a complete jam, especially of occlusal or incisal contact conditions.
A corresponding procedure can be inferred from DE 195 18 702 A1. Here the shape of the tooth to be restored and its surroundings are recorded and electronically stored first with the aid of a measuring facility in connection with which it can be a matter of a scanning system with optical or mechanical sensors or a 3D camera. In a second step, the image is interpreted. In a third step, the restoration is constructed. Then the digitalized signals obtained by means of CAD are fed into a numerically controlled machine (CAM) in order to manufacture the denture from a block of material. Recording the shape of the area to be restored takes place at a treatment site such as a dentist""s chair. In contrast, the evaluation of the measurement results as well as the manufacture of the denture itself takes place at a separate site. The CAD/CAM operations can moreover be conducted through a central computer.
A corresponding process nonetheless manifests the disadvantage that a sufficient configuration of the contact surface of the denture cannot take place. Rather, it frequently requires reprocessing.
CAD/CAM techniques for manufacturing a denture also achieve use according to EP 0 311 214 B 1, whereby for determining the shape of the denture to be constructed, a three dimensional photograph of a tooth prepared by a dentist in the mouth of the patient is generated.
From the literature citation Phillip Journal 7, pages 227 to 235, Computer-Modeled Denture with the Cicero System, an automatic manufacturing process for fixed restorations is known. Here an optical survey, sinter technology and computer-assisted manufacturing technology are used.
Underlying the present invention, among other things, is the problem of refining a process of the type mentioned at the beginning such that dentures are manufacturable by means of CAD/CM techniques in a simple manner, whereby at the same time it should be ensured that the contact surfaces of the denture have the necessary individual configuration so that a reprocessing is basically not required. Allowance should also be made for skull-related upper jaw position, especially in relation to the mandibular joint, its axis of rotation (hinge-axis) and motion pathways of the jaw joint capitulum.
In accordance with the invention, the problem is solved by the procedural steps:
Casting of upper and lower jaw for manufacturing upper jaw and lower jaw models as well as coordination of these in relation to each other by means of an articulator in a spatial orientation corresponding to the patient situation,
Coordination of at least two fixed points of the upper jaw model and/or of the lower jaw model or selected reference points toward the axis of rotation of the articulator or at least two reference points allocated to this,
Arrangement of the upper jaw model and arranging the lower jaw model in a measuring facility for determining the shape of the tooth, jaw area or jaw to be restored, whereby at least two fixed points are positioned in a predetermined setting to the coordinate system of the measuring facility for virtual representation of the axis of rotation of the articulator or the at least two reference points allocated to this,
Digitalization of the upper and lower jaw model or components of these models,
Joining together the digitizer data of the upper and lower jaw in harmony with data transmitted with the survey of the fixed points of the articulators,
Construction of the denture using CAD and
Manufacture of the denture using CAM.
It is especially provided that the known spatial orientation of the fixed points toward the axis of rotation (hinge-axis) of the articulator or further geometric data of the articulator are transmitted unambiguously into the measuring system through a reference element connected with the models of the upper and/or lower joint which is to be inserted only in a single position into the measuring system, and an allocation of virtual or real reference points of the axis of rotation (hinge-axis) of the articulator or further geometrical magnitudes of the articular in relation to the coordinate system of the measuring system or the data measured becomes possible.
Preferably any desired positioning of models in the measuring system can take place, and the fixed points toward the articulator are transmitted into the data record through an external reference element which is surveyed together with the models, or indirectly defines a defined position of the models, and in this way an allocation of virtual or real points of reference of the axis of rotation (hinge-axis) of the articulator or further geometrical magnitudes of the articulator toward the coordinate system of the measuring system or the measured data becomes possible.
It is provided in the refinement that more than two fixed points and/or a plane of reference are used for definition of the spatial positional reference of models toward the articulator, and are consequently, when transmitting into the measuring system upon realizing the models, the position fixed in the articulator, including the distance correlation of the models in the occlusal direction (contact points of the rows of teeth of both jaws (models)), are transmitted into the spatial orientation of the data records of upper and lower jaw.
In accordance with the invention, conventional techniques for manufacturing a denture with individually configured contact surfaces are used since for manufacturing and aligning upper and lower jaw models, customary dental recording techniques which are manageable and comprehensively tested come to be applied.
For determining the shape of the restoration, the upper jaw and lower jaw models are surveyed according to known techniques, whereby skull-related upper jaw positions can be taken into consideration through the definite coordination, for example, of the upper jaw model toward the axis of rotation of the articulator and therewith on the basis of the alignment of the lower jaw on the upper jaw of the unambiguous coordination of the lower jaw model on the axis of rotation of the articulator, and occlusal regions can be optimally recreated and processed. When surveying the upper jaw model and the lower jaw model, the axis of rotation of the articulator exists virtually, so that a clear coordination of the data exists with the result that an optimal determination of the shape of the tooth or jaw area to be restored takes place, taking into consideration an individual configuration of the contact surfaces. The use of more than two fixed points or reference planes in relation to the articulator permits transferring the position fixed in the articulator including the distance correlation of the models in the occlusal direction (contact points of rows of teeth of both jaws (models) into the spatial orientation of the data records of upper and lower jaw into the measuring system when realizing the model.
Owing to the fact that, when surveying the upper jaw model or lower jaw model, the axis of rotation as well asxe2x80x94if necessaryxe2x80x94a further reference point or a reference plane exist virtually, condylar path angles and/or Bennett angles and/or Fischer angles and/or side shift can be considered for computing the restoration so that an optimal denture is manufacturable.
In other words, in the patent, operations take place with conventional methods, whereby at the same time all of the advantages of computer-controlled work processes are used.
The base plate of the upper jaw model, which is clearly positionable in the articulator as well as in a measurement facility for determining the shape of the tooth to be restored and its surroundings, is particularly used for fixed points. Scanning the upper jaw model and the lower jaw model can take place mechanically or optically.
The corresponding digitized measurement results are connected while using the known spatial orientation of at least two fixed points of the upper and lower jaw models, or selected reference points toward the axis of rotation (hinge-axis) of the articulator or allocated reference points of this with the digitized available virtual reference points of the axis of rotation (hinge-axis) of the articulator, or additional geometric data of the articulator, subsequently virtually constructed on the basis of the values of the denture so obtained, and digital signals corresponding to the constructed denture are converted by means of CAM for manufacture of the denture.
It is especially provided that for determining shape, a CCD camera is used, whereby the areas of the upper jaw model and the lower jaw model to be recorded can, for example, be illuminated with a tape pattern. Other procedures such as the gray code procedure, the phase shift process, phase measuring processes or triangulation are likewise possible.